This project is concerned with an ultrastructural and cytochemical investigation of the lesions and their histogenesis associated with parasitic diseases, primarily paragonimiasis and schistosomiasis. Emphasis is being placed on the differentiation and function of host cell types involved in the immune response, inflammation and immunopathology, and the surface ultrastructure and topochemistry of the parasites. BIBLIOGRAPHIC REFERENCES: Lumsden, R. 1975. The surface ultrastructure and cytochemistry of parasitic helminths. Exp. Parasit. (Parasitological Reviews) 37: 267-339. McCracken, R. and R. Lumsden. 1975. Structure and function of parasite surface membranes. I. Mechanisms of Phlorizin inhibition of hexose transport by the cestode Hymenolepis diminuta. Comp. Biochem. Physiol. 50B: 153-157.